1. Field of the Invention
The present invention relates to a display device for vehicles which is located within the visual field of an operator of the vehicle, preferably within the operator's compartment. By use of the display device of the invention, the driver of the vehicle can accurately and unambiguously determine a variable, e.g., the speed, of the vehicle from the display device. The vehicles to which the display device can be fitted include land, sea, air and space vehicles but the invention is especially suited to land vehicles such as motor vehicles.
2. Description of related art
U.S. Pat. No. 3,694,084 to Citron is directed to a relative speed indicating means and more particularly to a visual display system for enabling an abstract visual comparison of the relative speed of one moving vehicle with respect to another and further to means capable of presenting an abstract visual display to the operator of a moving vehicle of the required desirable vehicle speed, the latter presentation being dictated remotely from a fixed station to the operator from means within the vehicle. In the particularly disclosed embodiment Citron employs, a stroboscopic perception phenomenon.
A Business Week article entitled G. M. and Hughes: Is the Marriage Fizzling!, of Feb. 12, 1990 discloses a fighter type "heads up display" that projects numerals indicating a motor vehicle's speed on the windshield of some Oldsmobile and Pontiac automobile models.
By contrast, my earlier application disclosed a projected display system whereby the necessity of an operator to refocus his eyes from the roadway to the speed indicating means was obviated. In such a projected display system, a point or points of light comprising a speed scale were projected onto a screen, for example, the windshield of a motor vehicle, and a discrete light indicating the actual speed of the vehicle was also projected onto the screen, so that the operator, by comparison of the location of the discrete light indicating the actual speed of the vehicle, to the point or points of light comprising the speed scale, could determine the actual speed of the vehicle, while maintaining customary driving eye focus, or by a quick glance slightly to the side of the line of vision.
The present invention presents a display system which is positioned so as to be directly viewable by an operator of a vehicle without the necessity to refocus the operator's eyes from the customary line of sight necessary to operate the vehicle thereby obviating the need for a projection mechanism. In the disclosed embodiments, interference with forward vision of the operator is minimized.